A typical vessel with an inboard fuel tank has a fuel port located on the deck, which is coupled by a fuel inlet line to the fuel tank (below deck) for filling the tank with fuel. At least one vent line is also typically coupled on one end to the fuel tank and coupled on the other end to a vent port, which is located below deck but above the water line of the vessel. The vent port is provided to permit fuel vapors to escape from the fuel tank and also to permit any excess fuel (e.g., when filling the fuel tank, when there is thermal expansion of the fuel, or agitation of the fuel in rough seas) to flow out of the tank. When filling such prior systems with fuel, the attendant typically determines when the tank is full by watching the vent port to see when the fuel begins to flow through the vent port into the water. This is a major cause of water pollution in marinas.
It is an object of the present invention to overcome many of the drawbacks and disadvantages of prior fuel systems.